This invention relates to an angle drive assembly for rotary cutters and more particularly to such an assembly which is adapted for use with multi-spindle rotary cutters carried by apparatus employed to mow or cut grass, underbrush and the like.
On medium to large size rotary cutters heretofore employed, each spindle has been driven by means of a separate angle drive which derives its motion from the power take-off of a tractor. For example, with a twin spindle machine, it is common practice to provide a primary drive unit which is connected directly to the power take-off of a tractor and transmits the motion to a spindle keyed on its output shaft and also to a secondary drive unit through a transmission drive having a second spindle keyed thereon.
Difficulties have been encountered with such prior art assemblies due to the fact that they leave a problem of significant importance unsolved, especially, when considering the high speeds involved and the resulting high rotational inertia of the spindles. That is, the rotational speed of the input shaft to the primary drive unit should be maintained constant, as far as possible, in order to avoid poor performance of the rotary cutter and to avoid excessive stresses on the components involved in the transmission of motion. Such nonuniform or irregular speeds encountered with prior art apparatus are usually the result of faulty alignment of the input shaft of the primary drive unit to the power take-off of the tractor, which alignment is almost impossible to achieve due to the necessity of shifting the hitch point of the rotary cutter relative to the tractor to effect different operations, such as the cutting of embankments, drainage ditches and the like. Also of particular importance is the equality of the angles formed both by the input shaft and the power take-off shaft relative to the intermediate shaft used to interconnect the input shaft with the power take-off shaft. Also, it is very desirable that such angles be maintained as small as feasible.